I've reviewed the post discussing this behavior how the Bandwidth monitors what goes on between my network and the Wan whereas IP Traffic monitors traffic on the network.

I still don't fully understand it.

If one of my devices downloads GBs of data, if it isn't doing so with the internet, where is it downloading the data from? I don't have anything that interesting on my home network.

I mentioned earlier that my VOIP device in IP Traffic shows that it uploaded .34 GBs. IP Traffic also shows that it downloaded .36 GBs. Regarding a VOIP device, it makes sense that the totals would be similar since it's carrying on a conversation that's two-way. But the upload of my VOIP device is more than the total upload traffic shown on my Bandwidth total.

I'm more inclined to believe the IP Traffic numbers than the Bandwidth numbers. But it seems excessive that I would download ~50GB of data in one day.

Fortunately (or unfortunately depending upon how you look at it ), Frontier doesn't track my bandwidth so I can't compare my numbers to what they are showing.